The Anderson intelligencer. [volume] (Anderson Court House, S.C.) 1860-1914, 1887-07-27
Our Great "Hot Waves"


The convoy of "hot waves" which
have just travelled across our continent
will make the summer of 1887 memorable
in meteorological annals. The last of
these waves eliminated Monday after
noon with temperature of lob degrees
on the Middle Atlantic seaboard. But
their duration has been as marked as
their intensity. Since the 4tb inst. there
has been scarcely a day when there was
not recorded over a large part Of the
country a heat exceeding 90 degrees.
The interesting questions of where
and how the hot waves originate have
been too little studied. Naturally we
should imagine that they are Graded in
the steaming bosom of the tropical
ocean, and are thence propagated as
sudden pulsations, or slowly drifted by
the return trade wind currents into the
interior of the continent. But this
theory will hardly stand. The heat rays
which strike the earths land surface are
arrested and accumulate or penetrate the.
soil by conduction until the solid crust
glows like the Sahara. But the heat
rays which strike the ocean surface do
not accumulate, and are soon dispersed
by wave action. The Specific heat" of
water, too, is so great that it takes as
much heat to raise the temperature of a
pound of water one degree Fahrenheit
as is required to raise that of nine pounds
of iron one degree. We must therefore
look elsewhere than to the tropical ocean
for the birthplace of our great "hot
waves"
That they emanate from the interior
of the continent itself seems more ten
able hypothesis. During the recent in.
tense heat it was a common thing 10 hear
of the mercury in "the nineties" over
the Northwest and the Upper Mississippi
Valley, when at the same hour on the
Gulf coast-so near the tropics-the
thermometer registered but little more
than 80 degrees. Although the sun has
been receding from us and commenced
his journey southwark on June %, and
on the I'd inst. the earth reached that
point in her orbit when she is most re-
mote from the fiery orb, temperature has
continually increased, because during
the long July days the soil accumulates
more heat than it can throw off during
the short nights. It is to this fact we
owe the prolongation of summer for
seventy days after the sun has started on
his southern journey. A week hence
the SUMS northern declination will have
decreased since the solstice June 21)
about FIVE degrees. But the reduction in
the amount of heat then received from
his rays on the northern tropic will be
only about 1-lS0th of that which he shot
down upon that line when he was yerti-
cally over it. :
1t follows from these considerations
that our great shot waves" are generated
in the interior of the continent by the
diurnal accumulation of soil temperature.
This massing of heat in the land by day,
however, would cause no such "hot
waves" as we have recently had, we're it
not that the water vapor in the atmcs'
phere is plentiful enough to prevent the
soil from radiating as much heat by
night.as it has stored up by day. The
earth's heat rapidly escapes through the
atmosphere into space unless the air is
charged with vapor. Professor Tyndall
and other physicists have demonstrated
that, though only one per cent. of the
atmosphere may be made up Of vapor
molecules, "this small modicum of
aqueous vapor intercepts fifteen times
the quantity Of heat Escaping from the
earth) stopped by the whole of the air
in which it is diffused." We may there
fore safely infer that the American "hot
waves" are formed in the great plains,
when the absolute humidity of the air,
in either its upper or lower strata, is ex-
ceptionally high. This inference is sus'
tained by the fact that among the highest
soil temperatures on record are these
observed by Sir John Herschel in the
humid atmosphere of the Cape of Good
Hope-as high as 15s Fabrenheit-and
by the traveller Stuart on the Macquarie
River, in New South Wales, where, he
says, "the ground was almost a molten
surface, and if a match fell upon it it
Immediately ignited."
If these physical laws governing the
formation OF our deadly waves of heat
we're applied in our meteorological re-
searches decided progress might be made
in predicting their occurrence, intensity
and duration. It would be great step
in this direction to take observations, by
means of captive balloons or other device,
of the actual humidity of the higher
atmospheric strata, and also of the upper
air currents, which have much to do with
the birth, the propagation and the break
ing up of the "hot wave."-New York
Herald